1. Field of the Invention
The present invention relates to a direct heat-sensitive recording method and device using a light-fixing-type heat-sensitive recording material.
2. Description of the Related Art
In heat recording, there is a heat transfer recording method and a heat-sensitive recording method. As compared with the heat transfer recording method, the heat-sensitive recording method is advantageous in that waste matter is not generated and the running costs are low. In order to carry out full color recording by using the heat-sensitive recording method, the three colors of yellow, magenta and cyan must be recorded independently. For example, there is a method in which heat-sensitive recording layers, which develop to different colors and have different heat recording sensitivities, are layered one upon the other, and the colors thereof are respectively formed by the magnitude of the heat. However, in this case, when the second color is recorded, the first color is formed. Therefore, a drawback arises in that it is not possible to form only the second color, and only the third color.
In order to overcome this drawback, a heat-sensitive recording method has been proposed which makes independent recording of the three colors possible by the introduction of a fixing process which is such that, when the second color is recorded, the first color is not formed, and when the third color is recorded, the second color is not formed.
As illustrated in FIG. 18, an image recording device 1 which effects full color recording in accordance with this method includes guide rollers 5 for guiding a color heat-sensitive recording material ("recording material") 3 to a recording section, a thermal head 7 and a platen roller 9 which are provided at the recording section, a pinch roller 11 and a capstan roller 13 which convey the recording material 3 in forward and reverse directions, and two fluorescent lamps 15a, 15b for exposure at different wavelengths (420 nm, 365 nm).
The processes of the full color recording carried out by the image recording device 1 are described hereinafter with reference to FIGS. 19 and 20. First, a yellow layer 17 of the supplied recording material 3 is developed (the color thereof is formed) by a low-energy amount of heat corresponding to recording information for the yellow layer 17. Thereafter, while the recording material 3 is conveyed in the reverse direction, the yellow layer 17 is light-fixed by ultraviolet light of 420 nm.
Next, while the recording material 3 is being conveyed in the forward direction again, the magenta layer 19 is developed by a medium-energy amount of heat corresponding to recording information for the magenta layer 19. Thereafter, while the recording material 3 is again conveyed in the reverse direction, the magenta layer 19 is light-fixed by ultraviolet light of 365 nm.
Finally, while the recording material 3 is again being conveyed in the forward direction, the cyan layer 21 is developed by a high-energy amount of heat corresponding to recording information for the cyan layer 21. The recording of three independent colors, i.e., full color recording, is thus completed.
FIG. 21 illustrates another image recording device 23. In this structure, three thermal heads 25a, 25b, 25c, which supply low-energy, medium-energy, and high-energy amounts of heat respectively, are disposed in order along the feeding direction of the recording material 3. A fluorescent lamp 27a of 420 nm is disposed between the low-temperature thermal head 25a and the medium-temperature thermal head 25b. A fluorescent lamp 27b of 365 nm is disposed between the medium-temperature thermal head 25b and the high-temperature thermal head 25c.
The processes of the full color recording carried out by this image recording device 23 are as follows, as illustrated in FIG. 22. First, the yellow layer 17 of the supplied recording material 3 is developed by the low-temperature thermal head 25a.
Immediately thereafter, the yellow layer 17 is light-fixed by the ultraviolet light of 420 nm. Next, the magenta layer 19 is developed by the medium-temperature thermal head 25b. Immediately thereafter, the magenta layer 19 is light-fixed by the ultraviolet light of 365 nm. Finally, the cyan layer 21 is developed by the high-temperature thermal head 25c. Thus, the full color recording of the recording material 3 is completed by conveying the recording material 3 one time in the feeding direction thereof.
However, in the image recording device 1 illustrated in FIG. 18, the recording material 3 which has been conveyed once must be conveyed in the reverse direction, so as to pass by the thermal head 7 three times. Therefore, a drawback arises in that an image cannot be recorded on the recording material at high speed. Further, in the image recording device 1, because the number of times the recording material 3 contacts the thermal head 7 is large, it is easy for the recording material 3 to be damaged or for portions of the recording material to not develop due to dirt or the like adhering thereto. Further, because the recording material 3 is conveyed plural times, there is also the problem of the registration shifting greatly.
Moreover, in the image recording device 23 illustrated in FIG. 21, although recording is completed by the recording material 3 being conveyed one time in the feeding direction, it is necessary to provide the three thermal heads 25a, 25b, 25c. Drawbacks arise in that the cost of the device increases, and the device becomes large. Further, in the image recording device 23, another drawback arises in that, because color formation by the low-temperature thermal head 25a is started after the leading end of the recording material 3 has reached the pinch roller 11, the blank space before recording begins is large.